Method and apparatus for spray foam insulating a pipe



METHOD AND APPARATUS FOR SPRAY FOAM INSULATING A PIPE Filed Aug. 27,1965 NOV. 25, 1969 R, B ER ET AL 2 Shets-Sheot 1 II fi-lu w m m e m RTwm M 5 Mn. rm HK .00 mm 9 mm M V/I/// l w & RR

. N. 22.55 n A M EEE; wmzaa mwmsazu v w. E o. OQ 4| I ll 5m 4111 fi AU v3 3 3 55% u wwwn Ew MN 25 6 Attorney NQV. 25, 1969 B ET AL 3,480,493

7 METHOD AND APPARATUS FOR SPRAY FOAM INSUUATING A PIPE Filed Aug. 27,1965 2 Sheets-Sheet 2 all M n W W A RICHARD HLB RlCH K|LpEm InventorsAttorney United States Patent ice 3,480,493 METHOD AND APPARATUS FORSPRAY FOAM INSULATING A PIPE Richard H. Bauer, West Caldwell, andRichard Kilpert, Berkeley Heights, N.J., assiguors to Esso Research andEngineering Company, a corporation of Delaware Coutlnuation-in-part ofapplication Ser. No. 420,083, Dec. 21, 1964. This application Aug. 27,1965, Ser. No. 486,591

Int. Cl. 133% 5/18, 31/14; B65h 81/06 U.S. Cl. 15678 Claims ABSTRACT OFTHE DISCLOSURE A method and apparatus for applying a sprayed plasticfoam insulation to a pipe wherein the pipe is cleaned and preheated toat least 90 F. prior to spray application of foam. The cleaning andpreheating assist in the foaming process and enhances the physical bondof the initial layer of sprayed foam to the pipe. A subsequentbitumastic and kraft paper vapor-barrier is subsequently applied to theexterior surface of the insulation.

This application is a continuation-in-part of applicants priorco-pending application Ser. No. 420,083 filed Dec. 21, 1964 and nowabandoned.

This invention relates to insulated pipes or conduits in general and inparticular to improved methods and apparatus for making and joiningsections of insulated pipe which employ as insulation one of the manycommercially available plastic foam materials such as polyurethane.

While it has been suggested that a pipe may be provided with a highefiiciency insulation cover by the application of a pre-moldedpolyurethane foam material thereabout, such technique is comparativelycostly. The present invention is specifically directed toward animproved and more economical method of providing insulation of this typeto a pipe. To this end, a novel process has been developed for the sprayapplication of a foamable insulation material to the surface of the pipeas the pipe is advanced and rotated past the spraying nozzle. Preferablythe noninsulated pipe is heated in advance of the spray application ofthe foamable insulation, which heat serves to accelerate and completethe foaming process occurring upon the deposition of the sprayedfoamable mixture upon the pipe. Thereafter in the novel method of theinvention, the pipe so insulated is continued to be advanced and rotatedwhile a subsequent water and vapor barrier in the form of a mastic orother 'type coating and paper wrapping is applied.

In the spray application of insulation in accordance with the inventionto a single pipe length, suitable means are provided to sense theleading and trailing ends of the pipe so that the application of theinsulationthereto is automatically omitted in the areas adjacent thepipe ends. The invention also provides for the sequential spray coatingof pipes with insulation, and for this purpose employs a novel means fortemporarily coupling the ends of adjacent pipe sections. After theinsulation of each pipe section, a subsequent two-stage application ofbituminous mastic is applied by spraying while the insulation is stillin a slightly tacky state. It has been found that the early applicationof the mastic coating at this stage produces a thicker surface skinformation on the insulation thereby increasing its durability andresistance to moisture absorption and the bond between the insulationand mastic. Another aspect of the present invention concerns a novelprocess for insulating the noninsulated end joint between two insulatedconduits after they have been joined in abutting fashion.

3,480,493 Patented Nov. 25, 1969 Accordingly, it is the principal objectof the invention to provide an improved method of applying insulation toa conduit.

Another object of the invention is to provide an insulated conduit whichhas improved thermal efficiency along its length as well as in the areaadjacent the pipe oints.

Another object of the invention is to provide an implioved foamed pipeinsulation having a thickened surface s in.

Another object of the invention is to provide a novel method forinsulating the welded end joint between adjacent sections of insulatedpipes.

Another object of the invention is to provide an improved coupling meansfor temporarily securing a plurality of pipe sections in end-to-endrelationship.

These and other objects and advantages of the invention will becomeapparent and the invention will be fully understood from the followingdescription and drawings in which:

FIG. 1 is a schematic flow diagram of the various steps of theinvention;

FIG. 2 is a cross-sectional view showing the manner in which the pipejoint is insulated in accordance with another aspect of the invention;

FIG. 3 is a cross-sectional view of adjacent pipe ends as they would betemporarily coupled during the insulation coating process; and

.FIG. 4 is a cross-sectional view of an insulated pipe in accordancewith the invention taken along line 44 of FIG. 2.

It will be understood that the drawings illustrate merely a preferredembodiment of the invention and that other embodiments are contemplatedwithin the scope of the claims as set forth.

Referring to FIG. 1 in particular, an uninsulated pipe 10 is advanced byconveyor means (not shown) in the direction of the dotted arrows througha cleaning and descaling station 14. After the temperature of thecleaned, advancing pipe 10 is increased by a heater 16, it enters achamber 20 for the spray application of a foamable insulation materialsuch as polyurethane. While for the purposes of convenience theinvention has been described in connection with the spray application of'a polyurethane foam, the invention is novel irrespective of thespecific type of foam insulation applied. Obviously, insulation such asfoamed glass, foamed polystyrene or others could be employed withoutdeparting from the spirit of the invention. Those skilled in the artwill readily appreciate that chamber 20 may include any suitable meansfor spraying and mixing a two-part foamable plastic wherein the foamingreaction starts within a relatively few seconds after foamablecomponents are mixed and sprayed. Prior to passage of the pipe 10through the heater 16 and spraying chamber 20, a pipe rotating means 18is effectiye to impart a rotational and lateral movement to the pipe asit is advanced throughout the remainder of the processing steps. In thisway the buildup of insulation material upon the pipes exterior in thechamber 20 is uniformly distributed and progressivelly applied to thepipe periphery. In one form of the invention, the pipe is rotated at 20"r.p.m. and the width of the area being sprayed is sufficiently widerelative to the speed of the lateral advance of the pipe so that any onepoint on the pipe surface is exposed to four passages through the sprayarea. If a two inch thickness of foamed insulation is desired, aispraydensity sufiicient to deposit a one-half inch thickness of insulationfor each revolution thereof would be selected. In one form of theinvention, a butane-fired ring-shaped heater has been employed. However,passage of steam within the pipe interior has been employed to equaladvantage to raise the surface temperature of the pipe to 90 to 120 F.,a preferred temperature for completion of the polyurethane foamingprocess. If service conditions warrant, a preliminary corrosionprotective coating may be applied prior to the application of the foaminsulation. Such a coating might be desirable when low temperaturefluids are conveyed in the pipeline and the likelihood of moisturecondensation is great or to guard against any unanticipated puncture ofthe exterior vapor barrier that may occur during installation orservice.

Thereafter as the pipe section continues to advance, it is processed bya water and vapor barrier application means indicated generally at 22.The means 22 includes a primer spray section 24 and a bitumastic spraysection 26. A minimum of time is allowed to elapse between the pipespassage from the end of the spray foam chamber 20 and the firstapplication of mastic primer spray at section 24. It has been found thatit is preferable to apply the spray 24 while the exterior of theinsulation is still in a slightly tacky or semi-cured state which hasthe beneficial effect of increasing the thickness of the surface skin.In this way, the insulation is made more durable and resistant tomoisture absorption. The consistency of the primer spray 24 is alsopreferably chosen to be more fluid than the spray applied at station 26so that small voids in the insulation surface are completely sealed andthe exterior surface smoothed for the subsequently applied heavierbitumastic coating. A wrapping station indicated at 28 is effective toapply a further vapor barrier layer to the still tacky bitumasticapplied at the preceding station 26. The vapor barrier applied atstation 28 is preferably a spirally wrapped kraft paper. It will beunderstood that for the purpose of the invention many difierent types ofwater and vapor barrier materials may be employed and they need notnecessarily be applied in this specific fashion.

In FIG. 1, the insulated pipe section is shown in its completed form aselement 12. Operating in conjunction with the means 20, 22 and 28 is acontrol means shown schematicaly at 30 which is effective to start andstop the application of insulation, primer spray, bitumastic spray, andwrapping paper at the appropriate points adjacent the ends of each pipesection. It will be understood that the control means 30 includessuitable sensing means which may be mechanical, optical or electricalfor determining the position of the ends of each pipe section so thatinsulation is not unnecessarily applied to the area of the pipe whichwill be subsequently welded. While an excess of insulation could beapplied to the pipe ends and be subsequently removed in the area of theweld, such removal would operate to rupture the closed cell structure ofthe insulation in its sprayed form in this area and would thereforeincrease the possibility of water penetrating the insulation.

Referring to FIG. 4, the insulated pipe in cross-section is illustrated.The expanded foam insulation 32 is of approximately two inch thicknessas previously related. The primer and water/vapor barrier coatingapplied by means 24 and 26 is indicated at 34. The paper applied atwrapping station 28 is indicated at 36.

In FIG. 2, a pair of adjacent pipe sections 10-10 are shown welded at38. It should be noted that the ends of the sprayed insulation layers 32terminate in rounded end portions 40 at a short distance displaced fromthe pipe end In insulating the welded pipe joint, a sheet ofsubstantially rigid material 42, such as galvanized iron, is wrapped ina cylindrical form about the outside diameter of the pipe insulation andsecured thereto by a pair of metal straps 44. The cylindrical sheet 42includes at least one aperture 46 through which sufficient foamablepolyurethane material 48 is poured or otherwise introduced so that theentire interior void area of the joint is filled. After the liquidpolyurethane 48 has foamed and set within the interior void, theaperture 46, cylindrical sheet 42, and the ends of the sheet 42 may becoated with a suitable mastic material (not shown) to insure a water/vapor barrier across this joint area. It will be seen that the pipejoint now includes a continuous insulation cover of substantially thesame thickness as the body portion of the adjacent pipe. The galvanizedsheet 42 may be left in the position shown so that a complete moisturebarrier is present along the entire length of the pipe sections.Alternatively, the sheet 42 may be removed and a conventional vaporbarrier applied. Should this latter procedure be used, it is desirableto apply a nonadhering type coating to the inside surface of sheet 42 toprevent rupture of the closed cell structure of the foam and allow reuseof the sheet without a cleaning step.

Referring to FIG. 3, the coupling that may be employed for joiningadjacent pipe sections 10-10 during their passage through the stepsillustrated in FIG. 1 is shown. The coupling body, generally indicatedat 50, includes a male half 52 and a female half 54. Each half includesmany similar elements which have been desig nated with like numerals.Each half includes an elongated hollow tube 56 which carries circularplate 58 secured to an end thereof. A resilient ring member 60 isdisposed adjacent the plate 58 and held in contact therewith by acompression plate 64. A threaded bolt 62 disposed at the bottom end ofthe tube 56 passes through a clearance aperture in plate 58 andthreadably engages the central portion of plate 64. A shield member 66is secured to a central portion of each of the tubes 56. The shield 66stabilizes the outer ends of each coupling half and prevents entry offoreign matter into the pipe end. One of the tubes 56 has an outsidediameter slightly smaller than the inside diameter of the adjacent tube56 so that it may be inserted therein. One tube is provided with a pairof projecting studs 68 which engage and lock into a conventional typebayonet slot 70 in the other tube. In use, each half of the coupling 50is inserted into the respective ends of the pipe sections to be joinedand the bolts 62 are tightened by a suitable tool (not shown) insertedinto the interior of the tube 56. Tightening of the bolts 62accomplishes the axial displacement of the compression plates 64 towardthe plates 58 to expand the outside diameter of rings 60 to engage thepipe inside di ameter. With each half of the coupling 50 thus secured toits respective pipe end, the pipe sections may be made fast by a smallaxial movement and angular rotation of one with respect to the other tolock the studs 68 with the slot 7-0. In this way the novel coupling ofthe invention provides for the easy and quick joining of the pipesections prior to advance through the insulating steps of FIG. 1. Afterthe insulation process has been com pleted, each of the couplings may bequickly disassembled to permit stocking of the individual pipe sectionsand reused indefinitely.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. The method of applying a plastic foam insulation to a pipe comprisingthe steps of conveying the pipe along an extended path, cleaning theexterior surface of said pipe as it is conveyed in said path, mixing andsequentially spraying a plurality of layers of constituents of afoamable plastic insulation onto the exterior surface of said pipe,heating said pipe to at least F. prior to the aforesaid spraying ofplastic insulation to assist the foaming process of the initial layer ofplastic insulation after it is sprayed upon the pipe exterior and toenhance the bond of the initial layer to said pipe, and applying awatervapor barrier to the exterior surface of the foamed plasticinsulation.

2. The method of claim 1 wherein said last mentioned step includesapplying a bitumastic first barrier prior to the completion of theinsulation foaming process to thereby inhibit further foaming and form athickened surface skin of plastic insulation and applying a spirallywrapped paper second Water-vapor barrier exterior of said first barrier.

3. The method of claim 2 including the further step of rotating saidpipe about its lengthwise axis during the steps of spraying saidinsulation and applying said watervapor barrier.

4. The method of claim 3 including the further steps of coupling aplurality of pipe sections in end-to-end relationship, and controllingthe spraying of said foamable plastic so as to interrupt the applicationof insulation adjacent the ends of the individual pipe sections.

5. The method of thermally insulating an elongated conduit with afoamable insulation material comprising the steps of advancing theconduit along its longitudinal axis, rotating the conduit about saidaxis as it is advanced, sensing the approach of the ends of the conduit,heating the conduit to at least 90 F. to assist in the foaming processof said foamable plastic insulation and to improve the bond thereof tosaid conduit, spraying a foamable plastic upon the conduit toprogressively build up the desired thickness of insulation, andcontrolling said spraying of insulation material in response to saidsensing of the condiut to discontinue the application of insulationmaterial adjacent the conduit ends.

6. The method of claim 5 including the further steps of applying a firstwater-vapor barrier of adhesive material to the foamed plasticinsulation and subsequently applying a spirally wrapped secondwater-vapor barrier to said adhesive material first barrier prior to itssetting to secure said second barrier to said first barrier.

7. The method of claim 6 including the further step of 8. Apparatus forapplying a plastic foam insulation to a pipe comprising means forconveying the pipe along an extended path, means for cleaning theexterior Surface of said pipe as it is conveyed in said path, means forheating said pipe to at least 90 F., means for mixing and spraying theconstituents of a foamable plastic insulation onto the exterior surfaceof said pipe, and means for applying a water-vapor barrier to theexterior surface of the foamed plastic insulation.

9. The apparatus of claim 8 wherein said last mentioned means includesmeans for applying a bitumastic first barrier prior to the completion ofthe insulation foaming process to thereby form a thickened surface skinof plastic insulation and applying a spirally wrapped paper secondbarrier exterior of said first barrier.

10. The apparatus of claim 9 including means for rotating said pipeabout its lengthwise axis during the sprayrotating said conduit at leastduring the spraying and water-vapor barrier application steps.

ing of said insulation and applying said water-vapor barrier.

References Cited UNITED STATES PATENTS 1,988,628 1/1935 McDonald et al.l38149 XR 2,857,931 8/1958 Lawton 13'8-149 XR 2,863,204 12/ 1958 Timothyet a1 25-38 XR 3,009,209 11/1961 Weinbrenner et al .2643l0 XR 3,041,7007/1962 Smith 25-38 3,307,590 3/1967 Carlson 138149 3,316,587 5/1967Scruggs 2643 10 XR HAROLD ANSHER, Primary Examiner G. W. MOXON II,Assistant Examiner US. Cl. X.R.

